Ok, interesting that the 4x6 1/8" wall steel was no heavier than the aluminum 3x6. I will probably use steel. I will see if I can find out the samson gantry wall thickness. That machine screams at a 1000 IPM cutting speed capability. Would love to bump into one of those for a song. About 3 years ago I saw a 4x4 Plasma cam table from a high school that never used it for $750. My Dodge Diesel had caught fire 3 days earlier and I just didn't have my head on straight and I decided not to get it. Kicking myself since.
What do you think about ease of loading/unloading of a plasmacam vs. the tables with the rails down below the tabletop height? I had in my mind to extend the rails past the end of the table also, so I can have gantry well out of the way for loading/unloading steel.
I have a bunch of 3"x3" 3/16" wall for legs of table, so I am hoping to incorporate it.
Once I have a fairly lightweight solution, I will see what electronics are needed to move it. I have the idea of steppers with a 3:1 reduction for detail and rack and pinion. This is based on my thinking a few years ago though. I have never looked at servo electronics because it was out of my budget before. I am not sure what the fastest cutting speed I would use, so I hope to match the electronics to be able to do so. I cannot imagine 1000 IPM like that Sampson, but I am ignorant at this point. It would seem that I will not need servos to have fast cutting speeds; but I have noted that the highest end tables tend to have servos, so I wonder??? Also, when I last thought to do this, I was married to the idea of Mach 3. Now, I am thinking possibly LinuxCNC. I thought about CandCNC interface to make the learning curve shorter and have support. I am also amiable to the idea of a light industrial controller syetem, but I do not know how to evaluate that yet, or how to source one. Last i was considering all this, I do not remember anyone doing that. Again, I will likely do some industrial espionage and flatter the masters by copying what works well.
For rails, I would lean toward linear rails at this point, but I have not done my diligence yet as to the quality of the cheaper rails nor the price of high-quality rails. If linear rails get disqualified, I will probably use hardened rails with double-v rollers; although I see no reason the linear rails won't be a good fit.
I did read on an old thread that a company changed to genuine Hi-Win rails because the good cheaper linear rails were inconsistent for hole placement, etc and it hurt their manufacturing process and probably parts replacement. For me though, I don't think that is an issue as I just need a quality rail once. If I put that many miles on it, I can go through a little extra effort to replace the rails. Also, things may have changed with manufacturers since that thread.
-Mike